Unnamed (3850 Nunatak west of Tarr Inlet)

Occurrence in Alaska, United States with commodities Copper, Silver, Zinc

Geologic information

Identification information

Deposit ID 10002244
MRDS ID A013146
Record type Site
Current site name Unnamed (3850 Nunatak west of Tarr Inlet)

Geographic coordinates

Geographic coordinates: -136.99407, 58.95361 (WGS84)
Relative position The occurrence is on a nunatak on a 3850-foot largely ice-mantled mountain two miles southwest of Tarr Inlet and three miles northwest of the point between Johns Hopkins Inlet and Tarr Inlet. It is in the NE 1/4 of section 1, T. 34 S., R. 50 E., of the Copper River Meridian and is located within 0.25 mile accuracy. The location is number 27 of Kimball and others (1978).
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Geographic areas

Country State
United States Alaska

Commodities

Commodity Importance
Copper Primary
Silver Secondary
Zinc Secondary

Materials information

Materials Type of material
Chalcopyrite Ore
Pyrite Ore
Pyrrhotite Ore
Quartz Gangue

Alteration

  • (Local) Skarn developed in calc-magnesian rocks. Skarn minerals include garnet and epidote.

Mineral occurrence model information

Model code 58
USGS model code 18a
Deposit model name Porphyry Cu, skarn-related
Mark3 model number 9

Host and associated rocks

  • Host or associated Host
    Rock type Plutonic Rock > Granitoid > Granite

Nearby scientific data

(1) -136.99407, 58.95361

Comments on the geologic information

  • Geologic Description = The occurrence area is extensively ice-mantled. Generally it is in an area where the country rocks are volcanic rocks of Permian age intruded by granitic rocks of Cretaceous age (Brew and others, 1978). At the occurrence, skarn-like pods of massive sulfide as much as 0.5 foot across occur in marble and volcanic rocks at a granitic contact. Silicate minerals in the skarn include actinolite, chlorite, diopside, epidote, and garnet. The sulfides are mainly pyrite and pyrrhotite, and minor chalcopyrite. Chip samples (Kimball and others, 1978, table C37, location 27) contained as much as 770 ppm copper, 190 ppm zinc, and 1.5 ppm silver.
  • Age = Tertiary.

Economic information

Economic information about the deposit and operations

Development status Occurrence
Commodity type Metallic

Comments on exploration

  • Status = Inactive

Mining district

District name Juneau

Comments on the workings information

  • Workings / Exploration = Surface occurrence only; samples of massive sulfide pods as much as 0.5 foot thick contained anomalous amounts of copper, zinc, and silver (Kimball and others, 1978, table C37, sample--location--number 27).

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS A013146
USGS Alaska Resource Data File ARDF MF047

Bibliographic references

  • Deposit

    Brew, D.A., Johnson, B.R., Grybeck, D., Griscom, A., Barnes, D.F., Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources of the Glacier Bay National Monument Wilderness Study Area, Alaska: U.S. Geological Survey Open-File Report 78-494, 670 p.

  • Deposit

    Kimball, A.L., Still, J.C., and Rataj, J.L., 1978, Mineral resources, in Brew, D. A., and others, Mineral resources of the Glacier Bay National Monument wilderness study area, Alaska: U.S. Geological Survey Open-File Report 78-494, p. C1-C375.

Comments on the references

  • Primary Reference = Kimball and others, 1978

General comments

Subject category Comment text
Deposit Model Name = Skarn, massive sulfide -- similar to porphyry copper, skarn related (Cox and Singer, 1986; model 18a).
Deposit Other Comments = Extensive ice cover which could conceal skarn- or porphyry copper-type deposits. The occurrence is in Glacier Bay National Park and Preserve.

Reporter information

Type Date Name Affiliation Comment
Reporter 09-APR-99 Hawley, C.C. Hawley Resource Group